NATURAL SCIENCES OF PHILADELPHIA. 179 



from those of the M. longimana and gig as, the known north Atlantic 

 species, as figured and described by Rudolphi and Gray. The transverse pro- 

 cess of the atlas is directed obliquely upward, truncate, deeper than long, 

 measuring half the depth of the articular face, its upper origin above the lat- 

 ter, and at the base of the neural arch. A rounded process, bearing the pos- 

 terior articular surface, projects into the upper part of the spinal canal. Of the 

 transverse processes of the axis, the superior is longer ; the canal is not 

 depressed, a little over half the diameter of the centrum. The superior 

 transverse processes increase in length to the fifth cervical, where they are 

 straight and slightly descending ; those of the sixth and seventh are well 

 developed. The last is the only one without inferior process ; the others are 

 well developed ; that of the fifth, three-fifths the diameter of the centrum, 

 and slightly angulated near the middle. Total number of vertebra?, 48, all free; 

 the neural spine is first smaller than the zygapophysis on the fortieth. The 

 neural arches and spines are remarkably elevated on the dorsal and lumbar 

 regions, somewhat as in the Catodontidae : e. g., in the 33d vertebrae, the ver- 

 tical diameter of the centrum is 9.75 inches, and the height of the arch and spine, 

 17.87 inches, or nearly double ; the position of the zygapophysis measures half 

 the elevation. The caudal series is short, and though a few vertebrae have pos- 

 sibly been lost, the series appears as though complete ; there are attachments 

 for eight chevron bones. There are fourteen pairs of ribs, of which the 

 anterior are simple-headed, and flattened distally ; the first is especially 

 dilated, double the width of the median, and presents a process on its pos- 

 terior edge near the extremity. This is present on the two following, being 

 successively nearer the extremity in each. Those of the last pair are slender, 

 and longer than iu Balaena, exceeding the second pair. The length of the 

 humerus and remainder of the fore limb is 9.05 feet, equal the length of the 

 cranium ; they supported a fluke equal in life to one-fifth the total length. 

 The breadth of the cranium measured below, from tip to tip of the orbital 

 processes of the frontal, 6.41 feet, or to the length as 8 to 11 ; in Rudolphrs 

 figure of the longimana, the proportions are as 8 to 14. Breadth between 

 coronoids of mandible, 5.75 feet. The ulna is much curved, and with two 

 proximal heads. Scapula, height, 29.6 inches; breadth, 44.4 inches. 



This specimen differs from those described by Gray * and Rudolphi, f in the 

 long inferior lateral processes of the posterior cervical vertebrae ; in the 

 former, they are said to exist on the anterior only. W. P. Flower, however, 

 in a valuable paperj on cetacean skeletons, describes two specimens, one in 

 the museum at Louvain, and the other at Brussels, which exhibit these 

 processes as far as the sixth and fifth vertebrae, respectively, but of diminished 

 length. In the specimen under consideration, that of the fifth is as long as 

 that of the second. 



The parallelopiped form and elevated position of the transverse processes, 

 and the internal process of the atlas, are not represented in Dr. Gray's figures. 



The cranium is broader, in proportion to its length, than represented by 

 Rudolphi, and shorter in proportion to the total, than in the measurements 

 of Flower and Moore : in these it is one-fourth, or more ; in the Maine speci- 

 men, one-fifth, or less. The fins are, also, relatively shorter, measuring one- 

 fifth of the length, instead of one-third. 



A most striking peculiarity of the species is the great elevation of the 

 arches and spinous processes of the dorsal, and especially the lumbar verte- 

 brae, reminding one of the structure in the toothed whales. The outline of 

 the skeleton is thus somewhat humped behind, presenting a contrast to that 

 represented by Rudolphi in the type specimen of the longimana, where the 

 elevation of the arches and spines does not exceed the diameter of the cen- 

 trum, on the lumbar region at least : on the 33d vertebra, the zygapophysis 



* Proc. Zool. Soc. Lond., 1864, 208. t Mem. Acad. Berlin, 1829, 13:. 



1 Pr. Z. S. Lond., 1864, 416-18. 



1865.] 



